Posted
by
Soulskill
on Tuesday August 14, 2012 @02:47PM
from the time-for-s'mores dept.

Diggester sends this quote from Nature News:
"Physicists at CERN's Large Hadron Collider have achieved the hottest man-made temperatures ever, by colliding lead ions to momentarily create a quark gluon plasma, a subatomic soup and unique state of matter that is thought to have existed just moments after the Big Bang. The results come from the ALICE heavy-ion experiment — a lesser-known sibling to ATLAS and CMS, which produced the data that led to the announcement in July that the Higgs boson had been discovered. ALICE physicists, presenting on Monday at Quark Matter 2012 in Washington DC, say they have achieved a quark gluon plasma 38% hotter than a record 4 trillion degree plasma achieved in 2010 by a similar experiment at Brookhaven National Laboratory in New York, which had been anointed the Guinness record holder."

So after years of wasting my life away here, I just now Google Image Searched her name (I don't believe it existed last time I looked for her), and now that I see her I KNOW WHAT THE DAMN FUSS IS ABOUT. DAMN! What do I do now that I've seen such beauty? Can I ever hope to fall in love with another woman? Will I ever see beauty in anybody else? Am I finally a true slashdotter? What do I do with myself now? How do we replicate this beauty so that we can all have her?

Indeed, on nature.com I would have expected something clearer like exponential notation.
Eric's answer to the first comment is even weirder:"It would be in Celsius. We’re metric around here. Cheers, Eric"
I'm pretty sure they work in Kelvin, for a US audience it would of course have been expressed as Rankin.

Indeed, on nature.com I would have expected something clearer like exponential notation.
Eric's answer to the first comment is even weirder:"It would be in Celsius. We’re metric around here. Cheers, Eric"
I'm pretty sure they work in Kelvin, for a US audience it would of course have been expressed as Rankin.

I believe the last record was reported in short-scale, so 4 trillion = 4 x 10^12

So I suspect this one must be 5 x 10^12 unless they've broken the record by a significant amount.:-)

If anything is published in a forum that also caters to Americans, you can safely assume that the short scale was used. While people elsewhere can convert, most Americans can't, whether this is due to ignorance, incompetence or hubris.

The long system makes more logical sense:

one billion = one million ^2one trillion = one million ^3one quadrillion = one million ^4

Curious (and too lazy to google)-- At 5.5 trillion K, they aren't going to just stick a thermometer in there. How do they measure how hot the plasma was?

Temperature is related to energy. So by measuring how much energy is in the quark-gluon plasma you can deduce its temperature.Another example is how do you determine the surface temperature of stars ? We sure as hell don't send thermometers to the sun, or to other stars. So how do we know that the surface temperature of the sun is roughly 6000 K ? You mesure how much energy the sun radiates, and by using a theoretical model (known as a black body) you can establish a relationship between amount of radiated energy and temperature. Therefore you can deduce the temperature of the sun (or of other stars).

Another example is how do you determine the surface temperature of stars ? We sure as hell don't send thermometers to the sun, or to other stars. So how do we know that the surface temperature of the sun is roughly 6000 K ? You mesure how much energy the sun radiates, and by using a theoretical model (known as a black body) you can establish a relationship between amount of radiated energy and temperature. Therefore you can deduce the temperature of the sun (or of other stars).

No soup for you!

The temperature of stars is determined by the spectral qualities of the emitted light, measured by diffraction grating or spectral photometrics. Different temperatures cause different elements to be in different states, and different elements absorb different parts of the light spectrum.

It's certainly not a direct measurement. They're determining the energy and then deriving the temperature from that. I've no idea how. At normal temperatures, I can see how you could use the specific heat of the material to do that. So much energy with so much material = a certain increase in temperature.I don't think that concept makes sense for a quark-gluon plasma however. The article mentioned that the measurement is relatively uncertain. I can imagine there would be problems associated with loss,

Probably using a specialized technique which I have no idea of. From TFA:

ALICE spokesman Paolo Giubellino says that the team’s measurement is relatively uncertain and, moreover, they haven’t yet converted an energy measurement into degrees. But he says there’s no reason to suspect that the conversion won’t produce a number like 5.5 trillion degrees. “It’s a very delicate measurement,” he says. “Give us a few weeks and it will be out.”

There are equations that relate to the frequencies of photons given off by the atoms as they collide. If you know how much matter you have injected into the system, how tightly confined the beams of atoms are, and how fast the ions are travelling, you can figure out the temperature at the time of collision.

Temperature is really just a measure of how much energy is stored in the electron orbitals.

Something feels hot simply because the electrons in your heat sensing receptor cells are gaining that much energy

Its a pretty tricky question. At this sort of temperature 5 trillion degrees corresponds to something like 500MeV, easily enough energy to create particle / anti-particle pairs from the vacuum. So, the energy of the incoming lead ions winds up being distributed among a much larger number of particles. As the fireball expands, some of these will decay into other particles. You can work out the fireball conditions from the types and energies of the particles that are produced, but I don't think its at all sim

IANAP, so anything I say about tht can be quite wrong. But from what I remember from explanations about quark-glun plasma, it gets in thermal equlibium faster than the energy can be dissipated. Thermal equilibrium also doesn't resemble what you get in atoms.

Also, it dissipates by emmiting particles, and ALICE is a particle detector, so the energy was calculated by observing how the plasma decayed.

Earliest calculatable time is the Planck second 10E-43 seconds. This is smallest resolvable time unit [wikipedia.org] in physical constants. This says [ucla.edu] 10^32 degrees K. At this temperature gravitation may unify with the other three universal forces.

It's "colder" but you have to understand that the universe cooled rapidly in the time immediately after the big bang. as the U expanded, the energy contained it was spread over a much larger volume, which effectively means that said volume had a lower temperature as time went on. The same is true for the quark-gluon plasma described in the article. Roughly speaking, this QGP would have the same properties that the universe had roughly 1 microsecond after the big bang (my estimate, could be off by quite a b

Yes, but creating a quark-gluon plasma is more than just energy. You have to get the nucleon (protons + neutrons) nice and high so you have quarks to deconfine to make the plasma. That's why BNL and CERN use heavy nuclei like gold and lead in these collisions. In a string theory experiment, you would probably just go for protons. My guess is that leptons (electrons, muons) would be a better choice for string theory experiments, but they lose too much energy going around the ring in cyclotron-style accelerat

It was a particularly cold winter, and we were already down to 3 Kevins (due to their low popularity at the time).

Kevin Thomas had flown out to be with his son's family for a wedding and got stuck in Boston for a whole week due to the weather. 2 Kevins left.

Kevin Lemmer was rushed to the hospital during my shift. I still remember the call from the EMTs as the ambulance was rushing toward us. "It's Lemmer. He's in bad shape. Drove right into the fucking ditch." We called the time of death at 6:15 PM.

At 6:16, all eyes turned to room 2217. Kevin Spencer was 82 and on his death bed with leukemia. His family being Catholic, he had already been given his last writes. If he couldn't hold out until Kevin Thomas returned, we would be at zero Kevins. Sure, we had 4 perfectly healthy Calvins, but they're just not the same.

It was 7:15 when Carla Brooks and her husband James burst through the main entrance. "She's not due for 2 weeks!", James exclaimed. As the staff bustled around getting the Brookses settled, they exchanged darting glances with each other. This was their first child, and they wanted to keep the baby's sex a secret. Of course, in a small town, secrets don't get kept. Nearly all of the hospital staff new that the child about to rip open Mrs. Brooks was indeed a boy.

The delivery was routine, and Kevin Brooks was born healthy, if a tad underweight, at 10:52 PM. Kevin Spencer was pronounced dead at 10:54.

It was, as they say, a close one. Kevin Thomas arrived two days later, the weather having finally cleared up. To this day, we still rib him about it.

Isn't "temperature" defined only for a system of many particles in some sort of thermodynamic equilibrium? I guess if you just crash highly accelerated particles into one another and convert the involved energies into a "temperature", you can arrive at pretty astonishing values, but you haven't really fulfilled the definition...

I'm not sure equilibrium is actually required, you could extrapolate from similar systems having similar energy distributed similarly among the constituent particles. Some such similar system might indeed be in equilibrium even of the one in the experiment isn't. And energy alone isn't enough to determine temperature -- there are pesky issues like heat capacity and such.

But I'd expect there have to be enough particles and energy states to make statistical talk is meaningful, and it's not clear to me that

I would imagine there there was more than enough particles/ sub particles present, even if there was only a zepto-mole of particles that Heisenberg would have said that two digits of precision is allowable.

This is, in fact, a hotly (pun intended) researched topic. The surprising thing is that the quark gluon plasma generated in relativistic heavy ion collisions seems to equilibrate _very_ quickly. The timescale observed for equilibration is ~ 1 fm/c which is the amount of time it takes light to propagate one femtometer. This translates into ~ 3 x 10^(-24) seconds. The plasma phase lives for ~ 8 fm/c at LHC, so it's important to establish equilibrium quickly, otherwise, as you've pointed out, you have don